Figure 2.

Glycerophospholipid structure and the site of action of phospholipases. The glycerophospholipid molecule consists of a glycerol-3-phosphate esterified at its sn-1 and sn-2 positions to non-polar fatty acids (R1 and R2, respectively) and, at its phosphoryl group to a polar head group, containing alcohol, X. Arrows indicate the sites of phospholipase-catalyzed hydrolysis. The carbon atoms of the glycerol backbone of the glycerophospholipid are indicated according to the stereochemical numbering (sn-1, sn-2 and sn-3).